The isolated perfused liver is being used to study cholesterol metabolism. The effect of diet, hormones and disease on the removal of chylomicron remnants will be studied. The kinetics of removal of IDL will also be assessed and the interaction between this lipoprotein class and others in the removal process will be determined. The effect of these lipoproteins on the production of new VLDL and HDL will also be measured. Other studies propose to elucidate the mechanism of the cholesterol induced inhibition of HMG CoA reductase by using an antibody to the enzyme. Finally the mechanism of remnant removal by liver is being investigated utilizing purified plasma membranes.